Geez dude... Want it gone that bad? Lol. I just laid some carbon fiber vinyl on the back of mine... Looks awesome! If all else fails, do something like that. Think all nice phones such as ours should be in a good protective case though. Good luck.

Sugar cubes are supposed to work as basically a mild sandpaper, but be wary of chemicals. Test them on a small bit first - I'm not sure what the back cover is made of but it may not get along with certain things!